This invention relates to audio/visual systems and, more particularly, to an improved multipurpose, film handling cassette for sound motion picture systems.
Motion picture systems including a multipurpose film cassette in which a film strip is contained without removal during exposure, processing and projection operations are described in prior U.S. Pat. Nos. 3,615,127 issued Oct. 26, 1961 to Edwin H. Land; 3,600,071 issued Aug. 17, 1971 to Rogers B. Downey; and 3,895,862 issued July 22, 1975 to Joseph A. Stella, et al. In accordance with the disclosures of these patents, the film cassette is first placed in a camera for exposure of the film strip therein in conventional fashion. After exposure, the cassette is loaded into a viewing device which first subjects the cassette to a sequence of operations during which the film strip is processed to develop a series of image transparency frames. The same viewing device then projects the developed image frames onto a screen for motion picture viewing.
The cassette system represented by the disclosure of these prior patents may be provided with an audio capability as disclosed in prior U.S. Pat. Nos. 3,604,790 issued Sept. 14, 1971 to Edwin H. Land and 3,856,387 issued Dec. 24, 1974 to William R. Wray, et al. In the audio/visual systems disclosed in these latter patents, a magnetic sound recording track is provided along one or both of the longitudinal borders of the cassette contained film strip and the cassette includes a provision for moving a loop of the film strip in operative relationship with a transducing head forming part of an audio system. While the arrangements disclosed in these patents provide generally acceptable audio reproduction, the narrow width of the audio tracks necessitated by their being carried directly on the film strip limits the level of sound quality which may be achieved or, conversely, increases the degree of sophistication or cost required of the audio system to achieve high fidelity.
In commonly assigned copending U.S. applications Ser. No. 869,131, filed Jan. 13, 1978 by Edwin H. Land, et al., and Ser. No. 899,872, filed Apr. 25, 1978, by Paul B. Mason, the sound track dimensional limitations of the prior systems are solved by providing in each cassette a separate audio tape in addition to the usual photographic film strip. Both the tape and the strip extend between and are interwound in nesting convolutions on cassette contained supply and takeup spools. In this way, both the tape and the film strip are simultaneously wound or unwound from the respective spools but the path through which the sound tape passes between the spools is different from that of the film strip. In particular, the film strip travels through a path including an exposure/projection station whereas the sound tape travels in a path including an audio transducing head and drive capstan.
The principal difficulty encountered with such dual web systems in the multipurpose cassettes having a provision for processing the motion picture film strip is the tendency for the sound tape to adhere to the emulsion or, at least, to processing fluid on the film strip emulsion during the period just following the deposition of processing fluid on the film strip. This problem is recognized in the above-noted application Ser. No. 899,872 and addressed by providing a mechanical stripping device for separating the sound tape from the film strip. Relative movement of the mechanical stripping device and the film strip, however, is likely to produce an undesirable wearing and possibly damage to one or both webs, particularly after repeated projection cycles.